Acquiring an image of a sample using MRI includes manipulating magnetic properties of the sample. Typically, the macroscopic sample acquires a magnetic moment when the sample is polarized along a primary axis defined by a principal magnetic field generated external to the sample. The sample reaches an essentially constant polarization state, known as a thermal equilibrium state, in the principal magnetic field. In order to acquire an image of the sample, the sample may be subject to time-varying and/or constant magnetic field gradients generated by gradient coils external to the sample. In addition, the sample may be subject to radio frequency (RF) pulses generated by RF coils external to the sample. The RF pulses, applied transverse to the primary axis defined by the external field, are used to manipulate the magnetization of the sample. Transverse components of the magnetization of the sample can induce time-varying currents in the RF coils, and the induced currents can be used to construct an image of the sample.